I recently checked the thickness of several plectrums I have. I was surprised as to quoted thickness to what I measured them with Vernier calipers. I checked the calipers against a reliable measurement to ensure it was reading correctly.
Here is quoted v actual for some I have
George Dennis quoted 1.3mm - actual 1.14mm - Hanks often used modern day pick.
Gibson
Heavy none quoted but are 0.9mm
ExHeavy none quoted but are 1,14mm
Medium none quoted but are 0.66mm
Fender
Thin none quoted but are 0.48mm
Medium none quoted but are 0.7mm
Heavy none quoted but are 0.96mm
ExHeavy none quoted but are 1.14mm
Dunlop Tortex Sharp
1.14 quoted but are 1.1mm
Dunlop Delrin500
1.14 quoted 1.14 measured.
The trend for many picks is thinner than quoted.
I have often preferred a ex heavy pick and it seems many are around 1.14 similar to the George Dennis Sharps I measured.
Hope you find this useful .
Roger.